A new method for controlling resonant frequencies of straightedge MSW resonators

We discuss a new technique to control the resonant frequencies of a straightedge magnetostatic wave (MSW) resonator without changing the external magnetic field intensity and the circuit parameters of a feedback load circuit. The method is to use multiple microstrip electrodes at the edges of the resonator and PIN diodes are connected to each electrode in series. Upon switching each PIN diode on or off, various incremental changes of the input admittance at the center electrode can be realized while the oscillation condition is sustained. Theoretical investigation reveals that very large and incremental resonant frequency shifts can be obtained. This indicates a possibility of digitally coded control of the resonant frequencies, which may be useful in mobile telephone applications. The possibility of the new technique was verified by a preliminary experiment